The invention relates to serving trays with an anti-slip surface.
A known method of manufacturing an anti-slip serving tray comprises providing a pile of sheets of paper impregnated with thermo-hardenable materials, such as melamines or phenolic resins. On this pile is placed a flexible cloth covered at least on its upper face by a layer of thermoplastic material such as PVC. The assembly is then pressed in a mould with the application of heat to transform protruding parts of said layer into synthetic rubber by polymerization, and to harden the stratified assembly.
Trays produced in this manner are rigid, light, have good mechanical strength and resistance to chemicals and, above all, have excellent anti-slip properties.
However, the method has an important drawback. During moulding, the resin-impregnated inner sheets give off gases and vapours that cannot completely escape through the albeit-porous PVC or other covering layer, and form bubbles trapped under said layer or its supporting cloth. When the tray is removed from the mould, these bubbles form superficial inequalities in the surface, which are perceptible and spoil the appearance of the tray.
An aim of the invention is to avoid this drawback in the above-mentioned method.